The present invention relates to devices for mixing and dispensing fluid materials and more particularly to hand held dispensers of the sort that are self cleaning so that when the fluid materials harden in the dispensing passage of the device, those passages can be cleaned of the hardened material.
Herefore, pressurized dispensing containers have been used for dispensing a mix of two or more fluid substances through a single nozzle. They include a chamber for mixing the fluids before they flow from the nozzle. Such dispensers are used for dispensing materials that cannot be pre-mixed and stored in the container, but must be mixed only as they are dispensed. Compositions such as glue, epoxy, polyurethan foam, paint, lacquer, insecticide, cosmetics, and even creamy whipped foods and the like require two different material to be separated in the dispenser and mixed together only at the time of use. For such dispensers and particularly for those that dispense glue, adhesive, or epoxy, the mixing chamber and the dispensing channels and orifices from the mixing chamber to the output must be cleaned out immediately after dispensing, or the mixed material will harden therein (or spoil) and make the dispenser useless.
Glue that sets by drying in air is often stored in liquid form under pressure and dispensed from a nozzle. The liquid glue flows from a container under pressure through a passage to the dispensing nozzle and the flow is controlled by a valve in the passage and/or by controlling the pressure. After dispensing, a crust of hardened glue forms at the nozzle where it is exposed to air. Most often, the crust is easily broken by the liquid glue behind it and so no extra step to clear the nozzle must be taken. On the other hand, some epoxy glue is a mix in predetermined proportions of liquid resin and hardner. Although neither the resin or the hardener alone will harden, they must be thoroughly mixed before dispensed and once mixed will harden even though not exposed to air and so the mixing passages and chambers and the dispensing nozzle must all be cleaned out thoroughly after each use. So also, reactive acrylic and urethane adhesives and coatings are mixtures of a resin and a catalyst that must be mixed thoroughly before dispensing and requires that the mixing chamber be cleared after each use.
Heretofor, liquid solvent has been used to flush out the passages and chambers to clear them of the mixed epoxy and so avoid blocking. That, of course, requires a ready supply of the solvent and means for feeding it into the dispenser passages and chambers Furthermore, cleaning out the passages and chambers in this way wastes solvent and requires a disposal for the wasted solvent.
It is an object to provide a dispenser of fluid material wherein the above described problems are avoided, diminished or compensated for.
It is another object of the present invention to provide a fluid material dispenser for a mixture of two or more different fluids that are mixed therein, incorporating means for cleaning out mixing and dispensing passages.
It is another object of the present invention to provide a method and means of mixing two different fluid materials and then cleaning out all parts thereof through which the mixed materials flow and closing off the material injection passages to those parts except when the apparatus is dispensing the mixture.
It is a further object to provide such a dispenser including a mixing chamber into which the two materials are fed and means for driving the mixing chamber in rotation to enhance mixing.